Jackson序列化失败时抛出KotlinReflectionInternalError与空列表和minifyEnabl

Question

在我的build.gradle文件中有minifyEnabled true假设我有一个模型

data class SomeModel(
val numberList: List<Int>
)

当numberList变量有某个值

时它会被正确序列化

SomeModel(listOf(1, 2, 3))

但如果numberList的内容为空，则序列化失败

SomeModel(listOf()) // or SomeModel(emptyList())

如果我将代码改为minifyEnabled false

，以上两种情况都可以正常工作我这样序列化

jsonMapper.writeValueAsString(someModel)

My Jackson'sJsonMapper是这样的

JsonMapper().apply {
enable(MapperFeature.INFER_PROPERTY_MUTATORS)
enable(MapperFeature.ACCEPT_CASE_INSENSITIVE_ENUMS)
configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
registerModule(KotlinModule())
}

我甚至在proguard-rules.pro文件中添加了类

-keep  class org.package.SomeModel {
<fields>;
}
# tried this also
-keep  class org.package.SomeModel {
*;
}

错误日志如下

kotlin.reflect.jvm.internal.KotlinReflectionInternalError: No accessors or field is found for property val kotlin.collections.EmptyList.serialVersionUID: kotlin.Long
at kotlin.reflect.jvm.internal.KPropertyImplKt.computeCallerForAccessor(KPropertyImpl.kt:240)
at kotlin.reflect.jvm.internal.KPropertyImplKt.access$computeCallerForAccessor(KPropertyImpl.kt:1)
at kotlin.reflect.jvm.internal.KPropertyImpl$Getter$caller$2.invoke(KPropertyImpl.kt:156)
at kotlin.reflect.jvm.internal.KPropertyImpl$Getter$caller$2.invoke(KPropertyImpl.kt:147)
at kotlin.reflect.jvm.internal.ReflectProperties$LazyVal.invoke(ReflectProperties.java:62)
at kotlin.reflect.jvm.internal.ReflectProperties$Val.getValue(ReflectProperties.java:31)
at kotlin.reflect.jvm.internal.KPropertyImpl$Getter.getCaller(Unknown Source:7)
at kotlin.reflect.jvm.ReflectJvmMapping.getJavaMethod(ReflectJvmMapping.kt:63)
at com.fasterxml.jackson.module.kotlin.KotlinAnnotationIntrospector.getCorrespondingGetter(KotlinAnnotationIntrospector.kt:145)
at com.fasterxml.jackson.module.kotlin.KotlinAnnotationIntrospector.hasRequiredMarker(KotlinAnnotationIntrospector.kt:110)
at com.fasterxml.jackson.module.kotlin.KotlinAnnotationIntrospector.access$hasRequiredMarker(KotlinAnnotationIntrospector.kt:23)
at com.fasterxml.jackson.module.kotlin.KotlinAnnotationIntrospector$hasRequiredMarker$hasRequired$1.invoke(KotlinAnnotationIntrospector.kt:40)
at com.fasterxml.jackson.module.kotlin.KotlinAnnotationIntrospector$hasRequiredMarker$hasRequired$1.invoke(KotlinAnnotationIntrospector.kt:23)
at com.fasterxml.jackson.module.kotlin.ReflectionCache.javaMemberIsRequired(ReflectionCache.kt:56)
at com.fasterxml.jackson.module.kotlin.KotlinAnnotationIntrospector.hasRequiredMarker(KotlinAnnotationIntrospector.kt:33)
at com.fasterxml.jackson.databind.introspect.AnnotationIntrospectorPair.hasRequiredMarker(AnnotationIntrospectorPair.java:318)
at com.fasterxml.jackson.databind.introspect.AnnotationIntrospectorPair.hasRequiredMarker(AnnotationIntrospectorPair.java:318)
at com.fasterxml.jackson.databind.introspect.POJOPropertyBuilder.getMetadata(POJOPropertyBuilder.java:229)
at com.fasterxml.jackson.databind.introspect.POJOPropertiesCollector._anyIndexed(POJOPropertiesCollector.java:1197)
at com.fasterxml.jackson.databind.introspect.POJOPropertiesCollector._sortProperties(POJOPropertiesCollector.java:1099)
at com.fasterxml.jackson.databind.introspect.POJOPropertiesCollector.collectAll(POJOPropertiesCollector.java:425)
at com.fasterxml.jackson.databind.introspect.POJOPropertiesCollector.getJsonValueAccessor(POJOPropertiesCollector.java:227)
at com.fasterxml.jackson.databind.introspect.BasicBeanDescription.findJsonValueAccessor(BasicBeanDescription.java:258)
at com.fasterxml.jackson.databind.ser.BasicSerializerFactory.findSerializerByAnnotations(BasicSerializerFactory.java:391)
at com.fasterxml.jackson.databind.ser.BasicSerializerFactory.buildCollectionSerializer(BasicSerializerFactory.java:705)
at com.fasterxml.jackson.databind.ser.BasicSerializerFactory.buildContainerSerializer(BasicSerializerFactory.java:647)
at com.fasterxml.jackson.databind.ser.BeanSerializerFactory._createSerializer2(BeanSerializerFactory.java:200)
at com.fasterxml.jackson.databind.ser.BeanSerializerFactory.createSerializer(BeanSerializerFactory.java:169)
at com.fasterxml.jackson.databind.SerializerProvider._createUntypedSerializer(SerializerProvider.java:1473)
at com.fasterxml.jackson.databind.SerializerProvider._createAndCacheUntypedSerializer(SerializerProvider.java:1441)
at com.fasterxml.jackson.databind.SerializerProvider.findPrimaryPropertySerializer(SerializerProvider.java:651)
at com.fasterxml.jackson.databind.ser.impl.PropertySerializerMap.findAndAddPrimarySerializer(PropertySerializerMap.java:72)
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter._findAndAddDynamic(BeanPropertyWriter.java:895)
E/AndroidRuntime:     at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:706)
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:770)
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178)
at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:480)
at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:319)
at com.fasterxml.jackson.databind.ObjectMapper._writeValueAndClose(ObjectMapper.java:4485)
at com.fasterxml.jackson.databind.ObjectMapper.writeValueAsString(ObjectMapper.java:3740)
at org.nvest.BiTool.test1(BiTool.kt:173)
at org.bharti.axa.ui.HomeScreenActivity$onCreate$4.onClick(HomeScreenActivity.kt:92)
at android.view.View.performClick(View.java:7509)
at android.view.View.performClickInternal(View.java:7486)
at android.view.View.access$3600(View.java:841)
at android.view.View$PerformClick.run(View.java:28709)
at android.os.Handler.handleCallback(Handler.java:938)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:236)
at android.app.ActivityThread.main(ActivityThread.java:8060)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)

Answer 1

错误提示No accessors or field is found for property val kotlin.collections.EmptyList.serialVersionUID: kotlin.Long

所以kotlin.reflect知道EmptyList.serialVersionUID，但是它找不到它让Jackson序列化空列表。因为它知道EmptyList.serialVersionUID，而它实际上是不可访问的，这可能意味着它在kotlin.collections.EmptyList的kotlin.Metadata中，而不是在类本身中。

由于这只发生在minifyEnabled = true上，r8似乎剥离了kotlin.collections.EmptyList.serialVersionUID，但实际上并没有更新kotlin.collections.EmptyList的kotlin.Metadata，以避免错误地表明该字段仍然存在。

这可能是r8的错误，r8是与android gradle插件一起打包的，所以将android gradle插件更新到最新的稳定版本应该可以解决这个问题。如果没有，我建议在Google Issue Tracker中提交r8 bug。